Get the deep 1 gallon pots. They are not very wide so they can be packed close together, but still allow a good bit of roots. technically roots like to spread out, and often do not use much of the middle of the pot, but for that small I doubt youll run into much of a rootbound issue. Have you considered a planter box instead?

A planter box can be very shallow, 5-6" deep, whatever width and length you want. This is really all they need, because they have tons and tons of space to spread out amongst eachother. You can pack a lot of plants close together this way. Just make sure its all the same strain (and preferably the same mother) so you get more uniform growth.
Racerx Reviewed by Racerx on . SOG HELP? What is the best Square pot size for the SOG method 6"? Plants Flowered @ 6" will be only 1 foot tall at harvest and i dont want root bound. Can a plant survive till harvest fine with a 6" pot? Rating: 5